The present invention relates to a data converter for protecting data communications against errors and modifications by a third party.
In packet communication, when a receive station has detected an error in any of the packets received, it in many cases discards the packet and sends a re-transmit request to a transmit station. In such a case, use is made of an error detector code. It has been reported that in a communication system of the type using encryption and decryption principles data can be protected against modifications by a third party if they are subjected to error detection coding before encryption, as disclosed in, for example, "Message Authentication" by R. R. Jueneman et al, IEEE Communication Magazine, Vol. 23, No. 9, September 1985, pages 29-40. However, when combined with a cryptograph, error detection coding cannot be made simple, as compared to a case without a cryptograph.